* Shell says investigating cause of fire
* Does not expect any impact on customers (Adds detail on production capacity)
SINGAPORE, Dec 11 (Reuters) - Royal Dutch Shell said a fire at its Singapore refinery-petrochemical site was extinguished on Sunday and no one was hurt in the incident.
The fire occurred at one of its manufacturing units on Bukom Island at about 10 a.m. (0200 GMT) and was extinguished shortly after by the site's firefighters, a company spokeswoman said in an e-mailed statement.
Shell was investigating the cause of the incident and did not expect any impact on its customers, she said.
Shell did not specify which unit had been affected.
The Bukom site, Shell's largest wholly-owned plant, has a 500,000 barrels per day (bpd) refinery and a steam cracker that produces more than 900,000 tonnes of ethylene a year. (Reporting by Florence Tan; Editing by Paul Tait and Joseph Radford)